1. Field of the Invention
The present invention relates to an electronic image recording apparatus, and more particularly to an arrangement of components of an image recording apparatus such as an electronic still camera and a digital video camera, which converts a captured image into a digital signal and records the digital signal onto a recording medium.
2. Description of Related Art
The circuits of the electronic still camera are generally classified into an analog circuit, a digital circuit and a power source circuit. The relatively large parts connected to the electronic circuits are a taking lens, a finder, a recording medium connector and a liquid crystal display (LCD) monitor.
Japanese Patent Provisional Publication Nos. 9-148710 and 1-220980 disclose the arrangement of the components in the electronic still camera.
Japanese Patent Provisional Publication No. 9-148710 discloses an arrangement of the analog circuit and the digital circuit that are mounted on one circuit board, and an arrangement of the circuit board and the recording medium connector. Although Japanese Patent Provisional Publication No. 9-148710 mentions providing a plate that shields the analog circuit, it fails to mention the arrangement of a plurality of circuit boards. According to Japanese Patent Provisional Publication No. 9-148710, the shielding plate must be provided as a special member and this is not desirable for reducing the number of parts and the size of the apparatus.
According to Japanese Patent Provisional Publication No. 1-220980, a memory card as the recording medium is arranged between the taking lens and a charge coupled device (CCD) as an imaging device, and a light passage hole is formed in the memory card on an area corresponding to the optical path between the taking lens and the CCD; however, it fails to disclose the shield between the circuit boards for reducing the effects of noises.
Recently, compact and lightweight electronic still cameras have been developed, which have high image quality, and thus, there is a desire to reduce the effects of noises and the size of the apparatus.
The present invention has been developed in view of the above-described circumstances, and has as its object the provision of an electronic image recording apparatus, which is constructed in the smallest size possible in an optimum arrangement of circuit boards and members such as a taking lens, and which achieves shielding (reducing the effects of electric and magnetic fields) between the circuit boards by utilizing components of the apparatus themselves.
To achieve the above-mentioned object, the present invention is directed to an electronic image recording apparatus comprising: an optical unit comprising a taking lens and an imaging device for converting a subject image formed by the taking lens into an analog image signal representing the subject image; a first circuit board on which an analog/digital converter is mounted, the analog/digital converter converting the analog image signal sent from the imaging device into a digital image signal; a second circuit board on which a compression/decompression circuit is mounted, the compression/decompression circuit compressing the digital image signal sent from the analog/digital converter to record onto a recording medium and decompressing a compressed digital image signal read from the recording medium; a recording medium chamber into which the recording medium is detachably inserted, the compressed digital image signal sent from the compression/decompression circuit being recorded onto the inserted recording medium, the compressed digital image signal recorded in the inserted recording medium being read from the inserted recording medium, the recording medium chamber being shielded with a wall having conductivity of electricity; and an image display unit comprising a display for displaying the image captured by the imaging device, the image display unit being shielded with a wall having conductivity of electricity; and wherein the first circuit board, the recording medium chamber, the second circuit board and the image display unit are arranged in that order and parallel to one another such that the recording medium chamber and the image display unit themselves serve as shields.
According to the present invention, the recording medium chamber and the image display unit of the electronic image recording apparatus have the shielding structure, and these two components are arranged appropriately with respect to the first and second circuit boards, so that the recording medium chamber and the image display unit can be utilized as shielding plates between the circuit boards.
This eliminates the necessity for special shielding plates and realizes the compact electronic image recording apparatus of high image quality. Moreover, the electronic image recording apparatus is hardly effected by noises.
In particular, since the optical unit including the imaging device is easily effected by noises, the electronic circuit members such as the first and second circuit boards are preferably perpendicular to the optical axis of the optical unit. Generally speaking, if a signal wire is parallel to a noise source, a signal on the wire tends to be affected by the noises. If the optical unit is perpendicular to the circuit boards, the signal wire transmitting the output signal from the imaging device is not parallel to the circuit boards, thereby reducing the effects of the noises. In this arrangement, since the components are arranged in the minimum size, the apparatus is compact.
A casing of the apparatus preferably has conductivity of electricity, by being made of metal for example, and it is possible to reduce the radiation of noises to the outside. The conductive casing and the inner shielding members, which are the recording medium chamber and the image display unit themselves, are connected to one another in order to reinforce the ground. This improves the shielding effects and the noise reducing effects.